Continuous Professional Development(CPD)

Which of the following built-in method is used to remove the last element from an array and return that element?

• last()

• pop()

• get()

• None of the above.

Answer explanation

The pop() method is the correct answer. It is used to remove the last element from an array and return that element.

Source:JavaScript MCQ (Multi Choice Questions) - javatpoint

What would be the output of the following Javascript code?

var string1 = "Fee"; 

 var intvalue = 10000; 

 alert( string1 + intvalue );

• Fee 10000

• 10000

• Fee10000

• Exception

Answer explanation

Fee10000 is the correct answer. After concatenation, both the strings are shown as a concatenated string.

Source:JavaScript MCQ (Multi Choice Questions) - javatpoint

Which of the following function of the Array object is used to add one or more elements to the front of an array and returns the new length of the array?

• splice()

• unshift()

• sort()

• toString()

Answer explanation

"unshift()" is the correct answer. It is used to add one or more elements to the front of an array and returns the new length of the array.

Source:JavaScript MCQ (Multi Choice Questions) - javatpoint

Which of the following is not a JavaScript Data Types?

• Boolean

• Undefined

• Number

• Float

Answer explanation

"Float" is the correct answer. JavaScript supports only the following Data types:Number, String, Boolean, Object, and Undefined

Source:JavaScript MCQ (Multi Choice Questions) - javatpoint

What will be the output of the following code snippet?

var a = 1;

var b = 0;

while (a <= 3) {

a++;

b += a * 2;

console.log(b);

}

• 4 10 18

• 1 2 3

• 1 4 7

• None of the above

Answer explanation

The loop will run 3 times, before meeting the exit condition. First value of b will be 2 2 = 4, followed by 4 + 3 2 = 10, and then value of 10 + 4 * 2 = 18.

Source:JavaScript MCQ (Multi Choice Questions) - javatpoint

 

Why is ref used in React js?

• To bind the function.

• To call A function

• to Directly access A DOM node

• To refer a another js file

Answer explanation

Ref is used to directly access the DOM node.